IGF1 and acromegaly: Guidelines do not advise on how to proceed in this case, however, taking into account that an IGFI value < 1.3 ULN is the limit considered as responsive to medical treatment in clinical trials [15, 16], in view of clinical suspicion, IGFI levels > 1.3 ULN would clearly indicate acromegaly, while a moderate IGFI elevation from 1 to 1.3 ULN should have to be further confirmed.